What is Merleau-Ponty's "perceptual faith"? Can it be summarized in a series of propositions, or is it less amenable to systematization than that?
See Maurice Merleau-Ponty, The Visible and the Invisible (1964), Ch.1 Reflection and Interrogation : THE PERCEPTUAL FAITH AND ITS OBSCURITY :
WE SEE THE THINGS THEMSELVES, the world is what we see: formulae of this kind express a faith [EDITOR's NOTE: Opposite the title of the section, the author notes: "Notion of faith to be specified. It is not faith in the sense of decision but in the sense of what is before any position, animal and [?] faith."] common to the natural man and the philosopher—the moment he opens his eyes; they refer to a deep-seated set of mute "opinions" implicated in our lives. But what is strange about this faith is that if we seek to articulate it into theses or statements, if we ask ourselves what is this we, what seeing is, and what thing or world is, we enter into a labyrinth of difficulties and contradictions.
And see the following section : SCIENCE PRESUPPOSES THE PERCEPTUAL FAITH AND DOES NOT ELUCIDATE IT.
Thus, "perceptual faith" is our animal belief that perception is perception of things existing in the external wotld.
Merleau-Ponty was both a distinguished, creative philosopher and (no contradiction) rather hard work for the reader. The following extract might make the phrase, 'perceptual faith', marginally clearer :
A permanent figure is to be distinguished from a temporary figure and appears at the moment of "maximum prise." At some point in perspectivally organized experience we gain an optimal view, revealing figures which will presumably never thereafter be proven illusory although they may of course cease to be effective and become merely virtual. At this point we presumptively unify perspectival experience in terms of these permanent figures so as to "engage the whole perceptual future" (PP, 415). The presumption that these permanent figures will never prove to be illusory is based merely upon a perceptual faith - we would be astonished upon disillusionment - but our experience is organized as if we had a perceptual guarantee to support this faith. At this point we are said to know particular natural objects (PP, pp. 343, 348, 367). Thus, once we have walked around and inside of a house, it appears definitely to be a house; we see all aspects of it as aspects of a house; and it would then seem incredible if on turning a corner for a second time we discovered it was merely a facade after all. (H. L. Dreyfus and S. J. Todes, 'The Three Worlds of Merleau-Ponty', Philosophy and Phenomenological Research, Vol. 22, No. 4 (Jun., 1962), pp. 559-565: 561-2.
Maurice Merleau-Ponty, Phenomenologie de la perception, Paris: 1945.
Maurice Merleau-Ponty, Phenomenology of Perception, tr. Colin Smith, Londin : Routledge, 2006, II, 3 & 4 passim.